package compiler.absyn;

import engine.query.Scan;
import storage.record.Schema;
public interface Expression {

	
	public boolean  isConstant();
	
	public boolean  isFieldName();
	
	public Constant asConstant();
	
	public String   asFieldName();
	
	public String toString();
	
	public Constant evaluate(Scan s);
	
	public boolean appliesTo(Schema sch);
}
